| 摘要 |
A light scanner in which, when forming an image on a scan surface by a scanning optical device through a deflector using light from a light source device, the scanning optical device includes first and second ftheta lenses. The first ftheta lens is a meniscus positive lens whose concave surface faces the deflector within a main scanning cross-sectional plane. The second ftheta lens is a meniscus lens whose convex surface faces the deflector within the main scanning cross-sectional plane. The shape of the second ftheta lens is such that the curvature from the optical axis thereof to both ends of a lens effective portion changes from convex to concave. The second ftheta lens is such that it is disposed closer to the deflector at both ends of the lens effective portion than at an apex thereof on the optical axis of the second ftheta lens. The invention provides a light scanner which properly corrects curvature of field and distortion in a main scanning direction and curvature of field and magnification in a subscanning direction, and which is suitable for high-definition print using a compact structure.
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